1. Field of the Invention
The present invention relates to a disk clamping mechanism that clamps a disk such as a CD (compact disk) between a turn table and a clamper. Specially, it relates to a disk clamping mechanism that can securely clamp a disk and make a smooth and easy transition from a clamped state to a clamp-released state of the disk.
2. Description of the Related Art
FIG. 5 is a side view to illustrate a compact disk (hereunder, abbreviated as CD) player incorporating the conventional clamping mechanism, in which FIG. 5A shows a clamp-released state, and FIG. 5B shows a clamped state.
As shown in FIG. 5, a disk drive unit 2 is provided inside an enclosure 1 of the CD player. The disk drive unit 2 is made up with a spindle motor 4 provided on a drive chassis 3, a turntable T fixed on a rotary shaft 4a of the spindle motor 4, and a pickup not illustrated, etc.
A disk clamping mechanism 5 is provided on the upper part of the drive chassis 3. The disk clamping mechanism 5 comprises a clamp arm 6 and a clamper 7 supported so as to freely rotate on the front end (Y1 side) of the clamp arm 6. The clamp arm 6 is supported on the base of the Y2 side to freely swing in the .alpha.1 direction (clamp-released direction) and in the .alpha.2 direction (clamped direction) against the drive chassis 3, with a swing shaft 8 serving as the fulcrum.
The clamp arm 6 has an operating member 6a that is formed bent downward in a virtually L-shape under the drive chassis 3. The operating member 6a has a clamp spring 10 attached, such as a coil spring or the like. By this clamp spring 10, the clamp arm 6 is energized in the .alpha.2 direction. A pressed part 9, which extends perpendicularly to the side view shown in FIG. 5, is provided on the front end (Y1 side) of the operating part 6a. This pressed part 9 is formed of a pin fastened to the operating member 6a, or the like.
A pressing member 11 that is moved in the Y1 and Y2 directions by a drive means (not shown) is provided so as to face the pressed part 9. As shown in FIG. 5A, as the pressing member 11 is moved in the Y2 direction, the pressed part 9 provided on the operating part 6a of the clamp arm 6 is pushed up in the Z1 direction by a taper 11a of the pressing member 11. Thereby, the clamp arm 6 is swung in the a1 direction, and the clamper 7 takes off from the turntable T into the clamp-released state. On the other hand, as shown in FIG. 5B, as the pressing member 11 is moved in the Y1 direction, the pressing member 11 takes off from the pressed part 9. At this moment, since the operating part 6a receives the energizing force from the clamp spring 10, the clamp arm 6 is swung in the .alpha.2 direction, and being clamped between the clamper 7 and the turntable T, a disk D is put in the clamped state. This clamping force is determined by the elasticity of the clamp spring 10.
A disk conveying means (not shown) is provided on the Y1 side of the disk drive unit 2. If the CD player is intended for a single disk insertion, the disk conveying means is, for example, a carrier roller. When the disk D (compact disk) is inserted from an insertion slot (not shown) provided on the front panel, the disk D is conveyed to the disk drive unit 2, receiving a feeding force by the carrier roller.
If the CD player is designed as a disk changer system, the conveying means is, for example, a tray conveying mechanism that pulls out trays inside a magazine. When the tray is pulled out in the Y2 direction, the disk mounted on the tray is transferred to the disk drive unit 2.
In the foregoing disk clamping mechanism 5, the clamp arm 6 is energized in the clamping direction by the elasticity of the clamp spring 10. The elongation of the clamp spring 10 becomes longer in the clamp-released state shown in FIG. 5A than in the clamped state shown in FIG. 5B. That is, if the elasticity in the clamping direction that acts on the clamp arm 6 in the clamped state is F0, and the elasticity in the clamping direction that acts on the clamp arm 6 in the clamp-released state is F1, F1&gt;F0.
That is, the energizing force becomes greater in the clamp-released state than in the clamped state. This situation does not change in such a structure that the arm of a torsion spring attached to the swing shaft 8 is hooked on the operating member 6a and the clamp arm 6 is energized in the clamping direction.
In the clamped state of the disk shown in FIG. 5B, it is necessary to increase the elasticity F0 to some extent in order to securely clamp the center of the disk D on the turntable T. Accordingly, as shown in FIG. 5A, the elasticity F1 that acts on the clamp arm 6 increases still more, when the clamp arm 6 is pushed up in the clamp-released direction.
As a result, when the pressing member 11 pushes up the pressed part 9 in opposition to the elasticity F1, the resistance that acts on the pressing member 11 becomes extremely increased, and a greater driving force to move the pressing member 11 in the Y2 direction becomes necessary, which inevitably requires a greater power consumption for a motor and the like. Further, the slide friction between the pressing member 11 and the pressed part 9 also increases, and the wear of components tends to increase.
Further, in the conventional example shown in FIG. 5, if the clamp arm 6 is swung to a great extent in the .alpha.1 direction by an external force during the process of manufacturing or maintenance, the clamp spring 10 will be stretched out to its breaking point, which is a problem to be resolved.
Therefore, it is conceivable to install a stopper (not shown) that restricts the swing range of the clamp arm 6 in the .alpha.1 direction. However, the installation of this stopper will create troubles in the assembly process while incorporating the clamp arm 6 onto the drive chassis 3, because the stopper becomes an obstacle. This will increase the number of components.
The present invention intends to solve those problems of the conventional technique. It is therefore an object of the invention to provide a disk clamping mechanism capable of varying the energizing force that acts on the clamp arm to an appropriate degree in correspondence with the clamped state and the clamp-released state, displaying an ample clamping force in the clamped state, and reducing the load that acts on a clamp switching means during the movement toward the clamp-released state.
Further, it is another object of the invention to provide a disk clamping mechanism that enables to give a limit to the swing angle of the clamp arm in the clamp-released direction without installing a stopper, whereby a breakage of the clamp spring or the like will not be created.